mbox series

[0/9] dts: Move to SoC-specific build rules

Message ID 20231227082405.2202246-1-sjg@chromium.org
Headers show
Series dts: Move to SoC-specific build rules | expand

Message

Simon Glass Dec. 27, 2023, 8:23 a.m. UTC
U-Boot builds devicetree binaries from its source tree. As part of the
Kconfig conversion, the Makefiles were updated to align with how this
is done in Linux: a single target for each SoC is used to build all the
.dtb files for that SoC.

Since then, the Makefiles have devolved in some cases, resulting in
lots of target-specific build rules. Also Linux has moved to using
subdirectories for each vendor.

Recent work aims to allow U-Boot to directly use devicetree files from
Linux. This would be easier if the directory structure were the same.
Another recent discussion involved dropping the build rules altogether.

This series makes a start at cleaning up some of the build rules, to
reduce the amount of code and make it easier to add new boards for the
same SoC.

One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
are not always the same. Given the large number of SoCs and boards
supported by U-Boot, it would be useful to align these where possible.


Simon Glass (9):
  microblaze: dts: Use the normal build rule
  nios2: dts: Use the normal build rule
  arm: at91: dts: Start an SoC-specific build rule
  arm: at91: dts: Complete conversion of dts build rules
  arm: at91: dts: Sort at91 rules
  arm: samsung: dts: Convert to SoC-specific build rules
  arm: ti: dts: Convert OMAP to SoC-specific build rules
  arm: qualcomm: dts: Convert to SoC-specific build rules
  arm: vexpress: dts: Convert to SoC-specific build rules

 arch/arm/dts/Makefile        | 174 ++++++++++++++---------------------
 arch/microblaze/dts/Makefile |   2 +-
 arch/nios2/dts/Makefile      |   2 +-
 3 files changed, 73 insertions(+), 105 deletions(-)

Comments

Tom Rini Dec. 27, 2023, 1:21 p.m. UTC | #1
On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:

> U-Boot builds devicetree binaries from its source tree. As part of the
> Kconfig conversion, the Makefiles were updated to align with how this
> is done in Linux: a single target for each SoC is used to build all the
> .dtb files for that SoC.
> 
> Since then, the Makefiles have devolved in some cases, resulting in
> lots of target-specific build rules. Also Linux has moved to using
> subdirectories for each vendor.
> 
> Recent work aims to allow U-Boot to directly use devicetree files from
> Linux. This would be easier if the directory structure were the same.
> Another recent discussion involved dropping the build rules altogether.
> 
> This series makes a start at cleaning up some of the build rules, to
> reduce the amount of code and make it easier to add new boards for the
> same SoC.
> 
> One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> are not always the same. Given the large number of SoCs and boards
> supported by U-Boot, it would be useful to align these where possible.

I don't know why we should start with this now, and further not being on
top of Sumit's series to remove our duplicate dts files. And that's
where we can have the conversation about for which cases it even makes
sense to build all of the dts files for a given SoC.
Simon Glass Dec. 28, 2023, 1:37 p.m. UTC | #2
Hi Tom,

On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
>
> On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
>
> > U-Boot builds devicetree binaries from its source tree. As part of the
> > Kconfig conversion, the Makefiles were updated to align with how this
> > is done in Linux: a single target for each SoC is used to build all the
> > .dtb files for that SoC.
> >
> > Since then, the Makefiles have devolved in some cases, resulting in
> > lots of target-specific build rules. Also Linux has moved to using
> > subdirectories for each vendor.
> >
> > Recent work aims to allow U-Boot to directly use devicetree files from
> > Linux. This would be easier if the directory structure were the same.
> > Another recent discussion involved dropping the build rules altogether.
> >
> > This series makes a start at cleaning up some of the build rules, to
> > reduce the amount of code and make it easier to add new boards for the
> > same SoC.
> >
> > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > are not always the same. Given the large number of SoCs and boards
> > supported by U-Boot, it would be useful to align these where possible.
>
> I don't know why we should start with this now, and further not being on
> top of Sumit's series to remove our duplicate dts files. And that's
> where we can have the conversation about for which cases it even makes
> sense to build all of the dts files for a given SoC.

This is a completely different series - there are no conflicts with
Sumit's series so it can be applied before or after it.

My goal here is to clean up our build rules, rather than just throwing
them all away, for reasons we have discussed previously. I filed [1]
to track that.

Regards,
Simon

[1] https://source.denx.de/u-boot/custodians/u-boot-dm/-/issues/15
Tom Rini Dec. 28, 2023, 2:23 p.m. UTC | #3
On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> Hi Tom,
> 
> On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> >
> > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> >
> > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > Kconfig conversion, the Makefiles were updated to align with how this
> > > is done in Linux: a single target for each SoC is used to build all the
> > > .dtb files for that SoC.
> > >
> > > Since then, the Makefiles have devolved in some cases, resulting in
> > > lots of target-specific build rules. Also Linux has moved to using
> > > subdirectories for each vendor.
> > >
> > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > Linux. This would be easier if the directory structure were the same.
> > > Another recent discussion involved dropping the build rules altogether.
> > >
> > > This series makes a start at cleaning up some of the build rules, to
> > > reduce the amount of code and make it easier to add new boards for the
> > > same SoC.
> > >
> > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > are not always the same. Given the large number of SoCs and boards
> > > supported by U-Boot, it would be useful to align these where possible.
> >
> > I don't know why we should start with this now, and further not being on
> > top of Sumit's series to remove our duplicate dts files. And that's
> > where we can have the conversation about for which cases it even makes
> > sense to build all of the dts files for a given SoC.
> 
> This is a completely different series - there are no conflicts with
> Sumit's series so it can be applied before or after it.
> 
> My goal here is to clean up our build rules, rather than just throwing
> them all away, for reasons we have discussed previously. I filed [1]
> to track that.

Yes, I'm saying we shouldn't be doing anything this series does until
after Sumit's series has landed. Along with the fact that I don't like
what's going on in this series.
Simon Glass Dec. 28, 2023, 3:09 p.m. UTC | #4
Hi Tom,

On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
>
> On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > Hi Tom,
> >
> > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > >
> > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > >
> > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > is done in Linux: a single target for each SoC is used to build all the
> > > > .dtb files for that SoC.
> > > >
> > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > lots of target-specific build rules. Also Linux has moved to using
> > > > subdirectories for each vendor.
> > > >
> > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > Linux. This would be easier if the directory structure were the same.
> > > > Another recent discussion involved dropping the build rules altogether.
> > > >
> > > > This series makes a start at cleaning up some of the build rules, to
> > > > reduce the amount of code and make it easier to add new boards for the
> > > > same SoC.
> > > >
> > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > are not always the same. Given the large number of SoCs and boards
> > > > supported by U-Boot, it would be useful to align these where possible.
> > >
> > > I don't know why we should start with this now, and further not being on
> > > top of Sumit's series to remove our duplicate dts files. And that's
> > > where we can have the conversation about for which cases it even makes
> > > sense to build all of the dts files for a given SoC.
> >
> > This is a completely different series - there are no conflicts with
> > Sumit's series so it can be applied before or after it.
> >
> > My goal here is to clean up our build rules, rather than just throwing
> > them all away, for reasons we have discussed previously. I filed [1]
> > to track that.
>
> Yes, I'm saying we shouldn't be doing anything this series does until
> after Sumit's series has landed. Along with the fact that I don't like
> what's going on in this series.

This seems to again be the disagreement over whether a single DT
should be build for each board, or all the DTs for an SoC?

Regards,
Simon
Tom Rini Dec. 28, 2023, 3:40 p.m. UTC | #5
On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> Hi Tom,
> 
> On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> >
> > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > >
> > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > >
> > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > .dtb files for that SoC.
> > > > >
> > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > subdirectories for each vendor.
> > > > >
> > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > Linux. This would be easier if the directory structure were the same.
> > > > > Another recent discussion involved dropping the build rules altogether.
> > > > >
> > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > same SoC.
> > > > >
> > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > are not always the same. Given the large number of SoCs and boards
> > > > > supported by U-Boot, it would be useful to align these where possible.
> > > >
> > > > I don't know why we should start with this now, and further not being on
> > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > where we can have the conversation about for which cases it even makes
> > > > sense to build all of the dts files for a given SoC.
> > >
> > > This is a completely different series - there are no conflicts with
> > > Sumit's series so it can be applied before or after it.
> > >
> > > My goal here is to clean up our build rules, rather than just throwing
> > > them all away, for reasons we have discussed previously. I filed [1]
> > > to track that.
> >
> > Yes, I'm saying we shouldn't be doing anything this series does until
> > after Sumit's series has landed. Along with the fact that I don't like
> > what's going on in this series.
> 
> This seems to again be the disagreement over whether a single DT
> should be build for each board, or all the DTs for an SoC?

It's about the disagreement on what we should be building, and what that
infrastructure looks like. I do not like adding extra rules for
"clarity" because they don't make things clearer, they lead to the
unclear mess we have today getting worse. Most instructions are _not_
"now take this dtb and this binary and .." but just "take this binary",
because we already have the rules and logic to ensure we build the
required dtbs. I also don't like the parts of this series that amount
to deck shuffling when we should just be taking the chairs away. There's
just not nor will there be a case for omap3/4/5 platforms of "change the
dtb", so building more is pointless. For other SoCs, there may be some
cases of "this could have been just a DT change", like
rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
dir, but the configs are different and the dts are different, so I don't
know that you could really just swap the dtbs.
Simon Glass Dec. 28, 2023, 7:48 p.m. UTC | #6
Hi Tom,

On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
>
> On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > Hi Tom,
> >
> > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > >
> > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > Hi Tom,
> > > >
> > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > >
> > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > >
> > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > .dtb files for that SoC.
> > > > > >
> > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > subdirectories for each vendor.
> > > > > >
> > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > >
> > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > same SoC.
> > > > > >
> > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > >
> > > > > I don't know why we should start with this now, and further not being on
> > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > where we can have the conversation about for which cases it even makes
> > > > > sense to build all of the dts files for a given SoC.
> > > >
> > > > This is a completely different series - there are no conflicts with
> > > > Sumit's series so it can be applied before or after it.
> > > >
> > > > My goal here is to clean up our build rules, rather than just throwing
> > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > to track that.
> > >
> > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > after Sumit's series has landed. Along with the fact that I don't like
> > > what's going on in this series.
> >
> > This seems to again be the disagreement over whether a single DT
> > should be build for each board, or all the DTs for an SoC?
>
> It's about the disagreement on what we should be building, and what that
> infrastructure looks like. I do not like adding extra rules for
> "clarity" because they don't make things clearer, they lead to the
> unclear mess we have today getting worse. Most instructions are _not_
> "now take this dtb and this binary and .." but just "take this binary",
> because we already have the rules and logic to ensure we build the
> required dtbs. I also don't like the parts of this series that amount
> to deck shuffling when we should just be taking the chairs away. There's
> just not nor will there be a case for omap3/4/5 platforms of "change the
> dtb", so building more is pointless. For other SoCs, there may be some
> cases of "this could have been just a DT change", like
> rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> dir, but the configs are different and the dts are different, so I don't
> know that you could really just swap the dtbs.

It is true that we have a different defconfig for each board, but IMO
that is not good. It is an artifact of the way the build system works.
IMO Kconfig should be used to define sensible defaults so that the
defconfigs are nearly empty. Perhaps config fragments can be part of
the mix, if we can agree on [1].

But if we let this genie out of the bottle, it will be impossible to
put back in. The devicetree should control the hardware in U-Boot and
it should be possible to use the same U-Boot proper on all boards
which use the same SoC.

Regards,
SImon

[1] https://patchwork.ozlabs.org/user/todo/uboot/?series=380278
Tom Rini Dec. 28, 2023, 8:44 p.m. UTC | #7
On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> Hi Tom,
> 
> On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> >
> > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > >
> > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > Hi Tom,
> > > > >
> > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > >
> > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > >
> > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > .dtb files for that SoC.
> > > > > > >
> > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > subdirectories for each vendor.
> > > > > > >
> > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > >
> > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > same SoC.
> > > > > > >
> > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > >
> > > > > > I don't know why we should start with this now, and further not being on
> > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > where we can have the conversation about for which cases it even makes
> > > > > > sense to build all of the dts files for a given SoC.
> > > > >
> > > > > This is a completely different series - there are no conflicts with
> > > > > Sumit's series so it can be applied before or after it.
> > > > >
> > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > to track that.
> > > >
> > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > what's going on in this series.
> > >
> > > This seems to again be the disagreement over whether a single DT
> > > should be build for each board, or all the DTs for an SoC?
> >
> > It's about the disagreement on what we should be building, and what that
> > infrastructure looks like. I do not like adding extra rules for
> > "clarity" because they don't make things clearer, they lead to the
> > unclear mess we have today getting worse. Most instructions are _not_
> > "now take this dtb and this binary and .." but just "take this binary",
> > because we already have the rules and logic to ensure we build the
> > required dtbs. I also don't like the parts of this series that amount
> > to deck shuffling when we should just be taking the chairs away. There's
> > just not nor will there be a case for omap3/4/5 platforms of "change the
> > dtb", so building more is pointless. For other SoCs, there may be some
> > cases of "this could have been just a DT change", like
> > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > dir, but the configs are different and the dts are different, so I don't
> > know that you could really just swap the dtbs.
> 
> It is true that we have a different defconfig for each board, but IMO
> that is not good. It is an artifact of the way the build system works.
> IMO Kconfig should be used to define sensible defaults so that the
> defconfigs are nearly empty. Perhaps config fragments can be part of
> the mix, if we can agree on [1].
> 
> But if we let this genie out of the bottle, it will be impossible to
> put back in. The devicetree should control the hardware in U-Boot and
> it should be possible to use the same U-Boot proper on all boards
> which use the same SoC.

We've never been past the point where a few examples of closely related
boards can re-use the same U-Boot build and just change the device tree.

It's going to be very SoC specific if we can ever do things like that,
and it will also likely in turn become a question of where did the
tricky bits that U-Boot used to do get shoved instead. You're not going
to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
ignoring all of the other omap3 boards) and get one binary that works on
both, and just uses DT. Let alone that no one wants to do that work.

You've mentioned Rockchip before as maybe a better example, but
https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
leading me to think that no, there's too much "this is what THIS
hardware does" that means that no, there's going to be hardware
variation that one must just handle in C. Or get more and new bindings
accepted upstream to try and make that be data driven, and also possibly
have to deal with "that's policy, not hardware" type arguments and so
forth.

> [1] https://patchwork.ozlabs.org/user/todo/uboot/?series=380278

Note that patchwork is annoying here and that for a series you've
assigned, you need to click on a patch in it, then the series link again
to get:
https://patchwork.ozlabs.org/project/uboot/list/?series=380278
which works for everyone. And append '&state=*' so that archive links
will still show it later once it's been accepted or superseded or what
have you.
Peter Robinson Dec. 29, 2023, 4:46 p.m. UTC | #8
On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
>
> On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > Hi Tom,
> >
> > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > >
> > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > Hi Tom,
> > > >
> > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > >
> > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > Hi Tom,
> > > > > >
> > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > >
> > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > >
> > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > .dtb files for that SoC.
> > > > > > > >
> > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > subdirectories for each vendor.
> > > > > > > >
> > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > >
> > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > same SoC.
> > > > > > > >
> > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > >
> > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > sense to build all of the dts files for a given SoC.
> > > > > >
> > > > > > This is a completely different series - there are no conflicts with
> > > > > > Sumit's series so it can be applied before or after it.
> > > > > >
> > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > to track that.
> > > > >
> > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > what's going on in this series.
> > > >
> > > > This seems to again be the disagreement over whether a single DT
> > > > should be build for each board, or all the DTs for an SoC?
> > >
> > > It's about the disagreement on what we should be building, and what that
> > > infrastructure looks like. I do not like adding extra rules for
> > > "clarity" because they don't make things clearer, they lead to the
> > > unclear mess we have today getting worse. Most instructions are _not_
> > > "now take this dtb and this binary and .." but just "take this binary",
> > > because we already have the rules and logic to ensure we build the
> > > required dtbs. I also don't like the parts of this series that amount
> > > to deck shuffling when we should just be taking the chairs away. There's
> > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > dtb", so building more is pointless. For other SoCs, there may be some
> > > cases of "this could have been just a DT change", like
> > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > dir, but the configs are different and the dts are different, so I don't
> > > know that you could really just swap the dtbs.
> >
> > It is true that we have a different defconfig for each board, but IMO
> > that is not good. It is an artifact of the way the build system works.
> > IMO Kconfig should be used to define sensible defaults so that the
> > defconfigs are nearly empty. Perhaps config fragments can be part of
> > the mix, if we can agree on [1].
> >
> > But if we let this genie out of the bottle, it will be impossible to
> > put back in. The devicetree should control the hardware in U-Boot and
> > it should be possible to use the same U-Boot proper on all boards
> > which use the same SoC.
>
> We've never been past the point where a few examples of closely related
> boards can re-use the same U-Boot build and just change the device tree.
>
> It's going to be very SoC specific if we can ever do things like that,
> and it will also likely in turn become a question of where did the
> tricky bits that U-Boot used to do get shoved instead. You're not going
> to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> ignoring all of the other omap3 boards) and get one binary that works on
> both, and just uses DT. Let alone that no one wants to do that work.
>
> You've mentioned Rockchip before as maybe a better example, but
> https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> leading me to think that no, there's too much "this is what THIS
> hardware does" that means that no, there's going to be hardware
> variation that one must just handle in C. Or get more and new bindings
> accepted upstream to try and make that be data driven, and also possibly
> have to deal with "that's policy, not hardware" type arguments and so
> forth.

Related I've seen issues with nearly identical rockchips devices that
use different memory chips that as a result need different U-Boot
builds because the early boot part needs to initialise a completely
different set of memory and the two different sets of rules aren't
detectable at run-time nor are they even small enough to fit into
smem.

> > [1] https://patchwork.ozlabs.org/user/todo/uboot/?series=380278
>
> Note that patchwork is annoying here and that for a series you've
> assigned, you need to click on a patch in it, then the series link again
> to get:
> https://patchwork.ozlabs.org/project/uboot/list/?series=380278
> which works for everyone. And append '&state=*' so that archive links
> will still show it later once it's been accepted or superseded or what
> have you.
>
> --
> Tom
Simon Glass Dec. 31, 2023, 12:45 p.m. UTC | #9
-Scott as it is bouncing

Hi,

On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
>
> On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> >
> > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > >
> > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > Hi Tom,
> > > > >
> > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > >
> > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > Hi Tom,
> > > > > > >
> > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > >
> > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > >
> > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > .dtb files for that SoC.
> > > > > > > > >
> > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > subdirectories for each vendor.
> > > > > > > > >
> > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > >
> > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > same SoC.
> > > > > > > > >
> > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > >
> > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > >
> > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > >
> > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > to track that.
> > > > > >
> > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > what's going on in this series.
> > > > >
> > > > > This seems to again be the disagreement over whether a single DT
> > > > > should be build for each board, or all the DTs for an SoC?
> > > >
> > > > It's about the disagreement on what we should be building, and what that
> > > > infrastructure looks like. I do not like adding extra rules for
> > > > "clarity" because they don't make things clearer, they lead to the
> > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > because we already have the rules and logic to ensure we build the
> > > > required dtbs. I also don't like the parts of this series that amount
> > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > cases of "this could have been just a DT change", like
> > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > dir, but the configs are different and the dts are different, so I don't
> > > > know that you could really just swap the dtbs.
> > >
> > > It is true that we have a different defconfig for each board, but IMO
> > > that is not good. It is an artifact of the way the build system works.
> > > IMO Kconfig should be used to define sensible defaults so that the
> > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > the mix, if we can agree on [1].
> > >
> > > But if we let this genie out of the bottle, it will be impossible to
> > > put back in. The devicetree should control the hardware in U-Boot and
> > > it should be possible to use the same U-Boot proper on all boards
> > > which use the same SoC.
> >
> > We've never been past the point where a few examples of closely related
> > boards can re-use the same U-Boot build and just change the device tree.
> >
> > It's going to be very SoC specific if we can ever do things like that,
> > and it will also likely in turn become a question of where did the
> > tricky bits that U-Boot used to do get shoved instead. You're not going
> > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > ignoring all of the other omap3 boards) and get one binary that works on
> > both, and just uses DT. Let alone that no one wants to do that work.
> >
> > You've mentioned Rockchip before as maybe a better example, but
> > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > leading me to think that no, there's too much "this is what THIS
> > hardware does" that means that no, there's going to be hardware
> > variation that one must just handle in C. Or get more and new bindings
> > accepted upstream to try and make that be data driven, and also possibly
> > have to deal with "that's policy, not hardware" type arguments and so
> > forth.

Oh wow yes that is crazy! But you can always check the compatible
string if really necessary. It would be nice to use a sysinfo driver
for this sort of thing. I should just be a full-time code reviewer...

>
> Related I've seen issues with nearly identical rockchips devices that
> use different memory chips that as a result need different U-Boot
> builds because the early boot part needs to initialise a completely
> different set of memory and the two different sets of rules aren't
> detectable at run-time nor are they even small enough to fit into
> smem.

Some of the differences are real/important, like memory settings, some
are not. For boards with enough SRAM that SPL can use DM/DT, we can
deal with these.

But even if SPL does need to be custom, that is better than having a
full, separate U-Boot for every single board.

>
> > > [1] https://patchwork.ozlabs.org/user/todo/uboot/?series=380278
> >
> > Note that patchwork is annoying here and that for a series you've
> > assigned, you need to click on a patch in it, then the series link again
> > to get:
> > https://patchwork.ozlabs.org/project/uboot/list/?series=380278
> > which works for everyone. And append '&state=*' so that archive links
> > will still show it later once it's been accepted or superseded or what
> > have you.

OK, yes, I should have noticed that sorry.

Regards,
Simon
Tom Rini Dec. 31, 2023, 2:01 p.m. UTC | #10
On Sun, Dec 31, 2023 at 05:45:00AM -0700, Simon Glass wrote:
> -Scott as it is bouncing
> 
> Hi,
> 
> On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
> >
> > On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> > >
> > > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > > Hi Tom,
> > > >
> > > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > > >
> > > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > > Hi Tom,
> > > > > >
> > > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > >
> > > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > > Hi Tom,
> > > > > > > >
> > > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > >
> > > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > > >
> > > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > > .dtb files for that SoC.
> > > > > > > > > >
> > > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > > subdirectories for each vendor.
> > > > > > > > > >
> > > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > > >
> > > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > > same SoC.
> > > > > > > > > >
> > > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > > >
> > > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > > >
> > > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > > >
> > > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > > to track that.
> > > > > > >
> > > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > > what's going on in this series.
> > > > > >
> > > > > > This seems to again be the disagreement over whether a single DT
> > > > > > should be build for each board, or all the DTs for an SoC?
> > > > >
> > > > > It's about the disagreement on what we should be building, and what that
> > > > > infrastructure looks like. I do not like adding extra rules for
> > > > > "clarity" because they don't make things clearer, they lead to the
> > > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > > because we already have the rules and logic to ensure we build the
> > > > > required dtbs. I also don't like the parts of this series that amount
> > > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > > cases of "this could have been just a DT change", like
> > > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > > dir, but the configs are different and the dts are different, so I don't
> > > > > know that you could really just swap the dtbs.
> > > >
> > > > It is true that we have a different defconfig for each board, but IMO
> > > > that is not good. It is an artifact of the way the build system works.
> > > > IMO Kconfig should be used to define sensible defaults so that the
> > > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > > the mix, if we can agree on [1].
> > > >
> > > > But if we let this genie out of the bottle, it will be impossible to
> > > > put back in. The devicetree should control the hardware in U-Boot and
> > > > it should be possible to use the same U-Boot proper on all boards
> > > > which use the same SoC.
> > >
> > > We've never been past the point where a few examples of closely related
> > > boards can re-use the same U-Boot build and just change the device tree.
> > >
> > > It's going to be very SoC specific if we can ever do things like that,
> > > and it will also likely in turn become a question of where did the
> > > tricky bits that U-Boot used to do get shoved instead. You're not going
> > > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > > ignoring all of the other omap3 boards) and get one binary that works on
> > > both, and just uses DT. Let alone that no one wants to do that work.
> > >
> > > You've mentioned Rockchip before as maybe a better example, but
> > > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > > leading me to think that no, there's too much "this is what THIS
> > > hardware does" that means that no, there's going to be hardware
> > > variation that one must just handle in C. Or get more and new bindings
> > > accepted upstream to try and make that be data driven, and also possibly
> > > have to deal with "that's policy, not hardware" type arguments and so
> > > forth.
> 
> Oh wow yes that is crazy! But you can always check the compatible
> string if really necessary. It would be nice to use a sysinfo driver
> for this sort of thing. I should just be a full-time code reviewer...
> 
> >
> > Related I've seen issues with nearly identical rockchips devices that
> > use different memory chips that as a result need different U-Boot
> > builds because the early boot part needs to initialise a completely
> > different set of memory and the two different sets of rules aren't
> > detectable at run-time nor are they even small enough to fit into
> > smem.
> 
> Some of the differences are real/important, like memory settings, some
> are not. For boards with enough SRAM that SPL can use DM/DT, we can
> deal with these.
> 
> But even if SPL does need to be custom, that is better than having a
> full, separate U-Boot for every single board.

I'm not sure that's a use case anyone else has or wants, and I disagree
that building a unique SPL and then more generic U-Boot is a win, in
practical and effort terms. The only win I see there is it would be part
of what I've said before about how I do not want the "XPL" series you've
talked about before, but instead think Yamada-san was right in hindsight
and in short we should have "fooboard_defconfig",
"fooboard_spl_defconfig" and "fooboard_tpl_defconfig" and you make each
config and build each config by itself. In that context, yes, you could
have barvend-fooboard_rev1_spl_defconfig,
barvend-fooboard_rev2_spl_defconfig and barvend-fooboard_defconfig to
get a more generic U-Boot build.  But nothing so much like an OS kernel
because we care about binary size and rarely does the OS vendor (but
some production cases in turn do), so outside of SoC-vendor where
showing off features is more important than size, most of the time, will
you see an actual use for SoC-generic U-Boot build.
Simon Glass Jan. 2, 2024, 2:06 p.m. UTC | #11
Hi Tom,

On Sun, Dec 31, 2023 at 7:01 AM Tom Rini <trini@konsulko.com> wrote:
>
> On Sun, Dec 31, 2023 at 05:45:00AM -0700, Simon Glass wrote:
> > -Scott as it is bouncing
> >
> > Hi,
> >
> > On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
> > >
> > > On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> > > >
> > > > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > > > Hi Tom,
> > > > >
> > > > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > >
> > > > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > > > Hi Tom,
> > > > > > >
> > > > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > >
> > > > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > > > Hi Tom,
> > > > > > > > >
> > > > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > >
> > > > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > > > >
> > > > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > > > .dtb files for that SoC.
> > > > > > > > > > >
> > > > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > > > subdirectories for each vendor.
> > > > > > > > > > >
> > > > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > > > >
> > > > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > > > same SoC.
> > > > > > > > > > >
> > > > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > > > >
> > > > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > > > >
> > > > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > > > >
> > > > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > > > to track that.
> > > > > > > >
> > > > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > > > what's going on in this series.
> > > > > > >
> > > > > > > This seems to again be the disagreement over whether a single DT
> > > > > > > should be build for each board, or all the DTs for an SoC?
> > > > > >
> > > > > > It's about the disagreement on what we should be building, and what that
> > > > > > infrastructure looks like. I do not like adding extra rules for
> > > > > > "clarity" because they don't make things clearer, they lead to the
> > > > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > > > because we already have the rules and logic to ensure we build the
> > > > > > required dtbs. I also don't like the parts of this series that amount
> > > > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > > > cases of "this could have been just a DT change", like
> > > > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > > > dir, but the configs are different and the dts are different, so I don't
> > > > > > know that you could really just swap the dtbs.
> > > > >
> > > > > It is true that we have a different defconfig for each board, but IMO
> > > > > that is not good. It is an artifact of the way the build system works.
> > > > > IMO Kconfig should be used to define sensible defaults so that the
> > > > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > > > the mix, if we can agree on [1].
> > > > >
> > > > > But if we let this genie out of the bottle, it will be impossible to
> > > > > put back in. The devicetree should control the hardware in U-Boot and
> > > > > it should be possible to use the same U-Boot proper on all boards
> > > > > which use the same SoC.
> > > >
> > > > We've never been past the point where a few examples of closely related
> > > > boards can re-use the same U-Boot build and just change the device tree.
> > > >
> > > > It's going to be very SoC specific if we can ever do things like that,
> > > > and it will also likely in turn become a question of where did the
> > > > tricky bits that U-Boot used to do get shoved instead. You're not going
> > > > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > > > ignoring all of the other omap3 boards) and get one binary that works on
> > > > both, and just uses DT. Let alone that no one wants to do that work.
> > > >
> > > > You've mentioned Rockchip before as maybe a better example, but
> > > > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > > > leading me to think that no, there's too much "this is what THIS
> > > > hardware does" that means that no, there's going to be hardware
> > > > variation that one must just handle in C. Or get more and new bindings
> > > > accepted upstream to try and make that be data driven, and also possibly
> > > > have to deal with "that's policy, not hardware" type arguments and so
> > > > forth.
> >
> > Oh wow yes that is crazy! But you can always check the compatible
> > string if really necessary. It would be nice to use a sysinfo driver
> > for this sort of thing. I should just be a full-time code reviewer...
> >
> > >
> > > Related I've seen issues with nearly identical rockchips devices that
> > > use different memory chips that as a result need different U-Boot
> > > builds because the early boot part needs to initialise a completely
> > > different set of memory and the two different sets of rules aren't
> > > detectable at run-time nor are they even small enough to fit into
> > > smem.
> >
> > Some of the differences are real/important, like memory settings, some
> > are not. For boards with enough SRAM that SPL can use DM/DT, we can
> > deal with these.
> >
> > But even if SPL does need to be custom, that is better than having a
> > full, separate U-Boot for every single board.
>
> I'm not sure that's a use case anyone else has or wants, and I disagree
> that building a unique SPL and then more generic U-Boot is a win, in
> practical and effort terms.

Think about firmware update where you could have an update that
supports all rk3399 boards, rather than 110 separate (and duplicate)
firmware updates.

> The only win I see there is it would be part
> of what I've said before about how I do not want the "XPL" series you've
> talked about before, but instead think Yamada-san was right in hindsight
> and in short we should have "fooboard_defconfig",
> "fooboard_spl_defconfig" and "fooboard_tpl_defconfig" and you make each
> config and build each config by itself. In that context, yes, you could
> have barvend-fooboard_rev1_spl_defconfig,
> barvend-fooboard_rev2_spl_defconfig and barvend-fooboard_defconfig to
> get a more generic U-Boot build.  But nothing so much like an OS kernel
> because we care about binary size and rarely does the OS vendor (but
> some production cases in turn do), so outside of SoC-vendor where
> showing off features is more important than size, most of the time, will
> you see an actual use for SoC-generic U-Boot build.

We'll see. The size cost for making things generic across an SoC is
likely very small, particularly if the settings are in the DT where
they belong. But I do accept we are not seeing the pressure yet.

For XPL, there are pros and cons, but I thought we talked about that
at the time and agreed that the need for Kconfig dependencies between
phases makes having separate defconfigs too painful?

Regards,
Simon
Tom Rini Jan. 2, 2024, 2:55 p.m. UTC | #12
On Tue, Jan 02, 2024 at 07:06:36AM -0700, Simon Glass wrote:
> Hi Tom,
> 
> On Sun, Dec 31, 2023 at 7:01 AM Tom Rini <trini@konsulko.com> wrote:
> >
> > On Sun, Dec 31, 2023 at 05:45:00AM -0700, Simon Glass wrote:
> > > -Scott as it is bouncing
> > >
> > > Hi,
> > >
> > > On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
> > > >
> > > > On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> > > > >
> > > > > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > > > > Hi Tom,
> > > > > >
> > > > > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > >
> > > > > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > > > > Hi Tom,
> > > > > > > >
> > > > > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > >
> > > > > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > > > > Hi Tom,
> > > > > > > > > >
> > > > > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > > >
> > > > > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > > > > >
> > > > > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > > > > .dtb files for that SoC.
> > > > > > > > > > > >
> > > > > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > > > > subdirectories for each vendor.
> > > > > > > > > > > >
> > > > > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > > > > >
> > > > > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > > > > same SoC.
> > > > > > > > > > > >
> > > > > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > > > > >
> > > > > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > > > > >
> > > > > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > > > > >
> > > > > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > > > > to track that.
> > > > > > > > >
> > > > > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > > > > what's going on in this series.
> > > > > > > >
> > > > > > > > This seems to again be the disagreement over whether a single DT
> > > > > > > > should be build for each board, or all the DTs for an SoC?
> > > > > > >
> > > > > > > It's about the disagreement on what we should be building, and what that
> > > > > > > infrastructure looks like. I do not like adding extra rules for
> > > > > > > "clarity" because they don't make things clearer, they lead to the
> > > > > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > > > > because we already have the rules and logic to ensure we build the
> > > > > > > required dtbs. I also don't like the parts of this series that amount
> > > > > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > > > > cases of "this could have been just a DT change", like
> > > > > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > > > > dir, but the configs are different and the dts are different, so I don't
> > > > > > > know that you could really just swap the dtbs.
> > > > > >
> > > > > > It is true that we have a different defconfig for each board, but IMO
> > > > > > that is not good. It is an artifact of the way the build system works.
> > > > > > IMO Kconfig should be used to define sensible defaults so that the
> > > > > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > > > > the mix, if we can agree on [1].
> > > > > >
> > > > > > But if we let this genie out of the bottle, it will be impossible to
> > > > > > put back in. The devicetree should control the hardware in U-Boot and
> > > > > > it should be possible to use the same U-Boot proper on all boards
> > > > > > which use the same SoC.
> > > > >
> > > > > We've never been past the point where a few examples of closely related
> > > > > boards can re-use the same U-Boot build and just change the device tree.
> > > > >
> > > > > It's going to be very SoC specific if we can ever do things like that,
> > > > > and it will also likely in turn become a question of where did the
> > > > > tricky bits that U-Boot used to do get shoved instead. You're not going
> > > > > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > > > > ignoring all of the other omap3 boards) and get one binary that works on
> > > > > both, and just uses DT. Let alone that no one wants to do that work.
> > > > >
> > > > > You've mentioned Rockchip before as maybe a better example, but
> > > > > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > > > > leading me to think that no, there's too much "this is what THIS
> > > > > hardware does" that means that no, there's going to be hardware
> > > > > variation that one must just handle in C. Or get more and new bindings
> > > > > accepted upstream to try and make that be data driven, and also possibly
> > > > > have to deal with "that's policy, not hardware" type arguments and so
> > > > > forth.
> > >
> > > Oh wow yes that is crazy! But you can always check the compatible
> > > string if really necessary. It would be nice to use a sysinfo driver
> > > for this sort of thing. I should just be a full-time code reviewer...
> > >
> > > >
> > > > Related I've seen issues with nearly identical rockchips devices that
> > > > use different memory chips that as a result need different U-Boot
> > > > builds because the early boot part needs to initialise a completely
> > > > different set of memory and the two different sets of rules aren't
> > > > detectable at run-time nor are they even small enough to fit into
> > > > smem.
> > >
> > > Some of the differences are real/important, like memory settings, some
> > > are not. For boards with enough SRAM that SPL can use DM/DT, we can
> > > deal with these.
> > >
> > > But even if SPL does need to be custom, that is better than having a
> > > full, separate U-Boot for every single board.
> >
> > I'm not sure that's a use case anyone else has or wants, and I disagree
> > that building a unique SPL and then more generic U-Boot is a win, in
> > practical and effort terms.
> 
> Think about firmware update where you could have an update that
> supports all rk3399 boards, rather than 110 separate (and duplicate)
> firmware updates.

I don't know who wants that actually is the problem I keep trying to
bring up. In other words, you're saying that the differences between
rock-pi-4c-rk3399_defconfig and khadas-edge-v-rk3399_defconfig are
unintentional and it's just due to different device trees and I say
they're intentional and the desire is not for a "kitchen sink" type
rk3399 primary U-Boot build. My evidence for this goes back to the SoCs
where we do have both "kitchen sink" and then board specific builds.
This would be things like how there's the am65x_evm configs, which
support all of the TI reference platforms (and others which follow the
EEPROM spec TI uses) and then also iot2050_defconfig, which also uses
the am65x SoC, but does not (would not) support the TI EEPROM layout and
instead does what it needs to do for their custom hardware revisions and
support all of those, instead.

What I think you keep wanting to aim for is fine and good and something
platforms can opt in to, and we have some doing it today. But it's still
at the end of the day a choice for the designers.

You say "110 separate (and duplicate)" and I disagree with the "(and
duplicate)" part of that. Could some platforms be condensed? Yes,
likely. But figuring out how to do that starts with figuring out why
they're separate to start with.

> > The only win I see there is it would be part
> > of what I've said before about how I do not want the "XPL" series you've
> > talked about before, but instead think Yamada-san was right in hindsight
> > and in short we should have "fooboard_defconfig",
> > "fooboard_spl_defconfig" and "fooboard_tpl_defconfig" and you make each
> > config and build each config by itself. In that context, yes, you could
> > have barvend-fooboard_rev1_spl_defconfig,
> > barvend-fooboard_rev2_spl_defconfig and barvend-fooboard_defconfig to
> > get a more generic U-Boot build.  But nothing so much like an OS kernel
> > because we care about binary size and rarely does the OS vendor (but
> > some production cases in turn do), so outside of SoC-vendor where
> > showing off features is more important than size, most of the time, will
> > you see an actual use for SoC-generic U-Boot build.
> 
> We'll see. The size cost for making things generic across an SoC is
> likely very small, particularly if the settings are in the DT where
> they belong. But I do accept we are not seeing the pressure yet.

Yes, I think we're well past the point where it's a case of needing to
see the implementation rather than talking about it over and over.

> For XPL, there are pros and cons, but I thought we talked about that
> at the time and agreed that the need for Kconfig dependencies between
> phases makes having separate defconfigs too painful?

I recall there being a large number of issues.
Simon Glass Jan. 2, 2024, 11:51 p.m. UTC | #13
Hi Tom,

On Tue, Jan 2, 2024 at 7:55 AM Tom Rini <trini@konsulko.com> wrote:
>
> On Tue, Jan 02, 2024 at 07:06:36AM -0700, Simon Glass wrote:
> > Hi Tom,
> >
> > On Sun, Dec 31, 2023 at 7:01 AM Tom Rini <trini@konsulko.com> wrote:
> > >
> > > On Sun, Dec 31, 2023 at 05:45:00AM -0700, Simon Glass wrote:
> > > > -Scott as it is bouncing
> > > >
> > > > Hi,
> > > >
> > > > On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
> > > > >
> > > > > On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> > > > > >
> > > > > > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > > > > > Hi Tom,
> > > > > > >
> > > > > > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > >
> > > > > > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > > > > > Hi Tom,
> > > > > > > > >
> > > > > > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > >
> > > > > > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > > > > > Hi Tom,
> > > > > > > > > > >
> > > > > > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > > > > > .dtb files for that SoC.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > > > > > subdirectories for each vendor.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > > > > > >
> > > > > > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > > > > > same SoC.
> > > > > > > > > > > > >
> > > > > > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > > > > > >
> > > > > > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > > > > > >
> > > > > > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > > > > > >
> > > > > > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > > > > > to track that.
> > > > > > > > > >
> > > > > > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > > > > > what's going on in this series.
> > > > > > > > >
> > > > > > > > > This seems to again be the disagreement over whether a single DT
> > > > > > > > > should be build for each board, or all the DTs for an SoC?
> > > > > > > >
> > > > > > > > It's about the disagreement on what we should be building, and what that
> > > > > > > > infrastructure looks like. I do not like adding extra rules for
> > > > > > > > "clarity" because they don't make things clearer, they lead to the
> > > > > > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > > > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > > > > > because we already have the rules and logic to ensure we build the
> > > > > > > > required dtbs. I also don't like the parts of this series that amount
> > > > > > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > > > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > > > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > > > > > cases of "this could have been just a DT change", like
> > > > > > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > > > > > dir, but the configs are different and the dts are different, so I don't
> > > > > > > > know that you could really just swap the dtbs.
> > > > > > >
> > > > > > > It is true that we have a different defconfig for each board, but IMO
> > > > > > > that is not good. It is an artifact of the way the build system works.
> > > > > > > IMO Kconfig should be used to define sensible defaults so that the
> > > > > > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > > > > > the mix, if we can agree on [1].
> > > > > > >
> > > > > > > But if we let this genie out of the bottle, it will be impossible to
> > > > > > > put back in. The devicetree should control the hardware in U-Boot and
> > > > > > > it should be possible to use the same U-Boot proper on all boards
> > > > > > > which use the same SoC.
> > > > > >
> > > > > > We've never been past the point where a few examples of closely related
> > > > > > boards can re-use the same U-Boot build and just change the device tree.
> > > > > >
> > > > > > It's going to be very SoC specific if we can ever do things like that,
> > > > > > and it will also likely in turn become a question of where did the
> > > > > > tricky bits that U-Boot used to do get shoved instead. You're not going
> > > > > > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > > > > > ignoring all of the other omap3 boards) and get one binary that works on
> > > > > > both, and just uses DT. Let alone that no one wants to do that work.
> > > > > >
> > > > > > You've mentioned Rockchip before as maybe a better example, but
> > > > > > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > > > > > leading me to think that no, there's too much "this is what THIS
> > > > > > hardware does" that means that no, there's going to be hardware
> > > > > > variation that one must just handle in C. Or get more and new bindings
> > > > > > accepted upstream to try and make that be data driven, and also possibly
> > > > > > have to deal with "that's policy, not hardware" type arguments and so
> > > > > > forth.
> > > >
> > > > Oh wow yes that is crazy! But you can always check the compatible
> > > > string if really necessary. It would be nice to use a sysinfo driver
> > > > for this sort of thing. I should just be a full-time code reviewer...
> > > >
> > > > >
> > > > > Related I've seen issues with nearly identical rockchips devices that
> > > > > use different memory chips that as a result need different U-Boot
> > > > > builds because the early boot part needs to initialise a completely
> > > > > different set of memory and the two different sets of rules aren't
> > > > > detectable at run-time nor are they even small enough to fit into
> > > > > smem.
> > > >
> > > > Some of the differences are real/important, like memory settings, some
> > > > are not. For boards with enough SRAM that SPL can use DM/DT, we can
> > > > deal with these.
> > > >
> > > > But even if SPL does need to be custom, that is better than having a
> > > > full, separate U-Boot for every single board.
> > >
> > > I'm not sure that's a use case anyone else has or wants, and I disagree
> > > that building a unique SPL and then more generic U-Boot is a win, in
> > > practical and effort terms.
> >
> > Think about firmware update where you could have an update that
> > supports all rk3399 boards, rather than 110 separate (and duplicate)
> > firmware updates.
>
> I don't know who wants that actually is the problem I keep trying to
> bring up. In other words, you're saying that the differences between
> rock-pi-4c-rk3399_defconfig and khadas-edge-v-rk3399_defconfig are
> unintentional and it's just due to different device trees and I say
> they're intentional and the desire is not for a "kitchen sink" type
> rk3399 primary U-Boot build. My evidence for this goes back to the SoCs
> where we do have both "kitchen sink" and then board specific builds.
> This would be things like how there's the am65x_evm configs, which
> support all of the TI reference platforms (and others which follow the
> EEPROM spec TI uses) and then also iot2050_defconfig, which also uses
> the am65x SoC, but does not (would not) support the TI EEPROM layout and
> instead does what it needs to do for their custom hardware revisions and
> support all of those, instead.

OK, but this code should be in drivers which we can enable or disable,
wouldn't it? We are trying to move away from board.c files.

I am not saying that all the defconfig differences are unintentional,
just that we should really rationalise them, so it is clear what needs
to be enabled for each board, and what is just by accident. Part of
that is using Kconfig more than defconfig. Another part might be
fragments if we can agree a way to describe a defconfig made up of
fragments ([2] is still hanging about).

>
> What I think you keep wanting to aim for is fine and good and something
> platforms can opt in to, and we have some doing it today. But it's still
> at the end of the day a choice for the designers.

Indeed. I just want to make it easier to be generic than to be specific.

>
> You say "110 separate (and duplicate)" and I disagree with the "(and
> duplicate)" part of that. Could some platforms be condensed? Yes,
> likely. But figuring out how to do that starts with figuring out why
> they're separate to start with.

I mean there are 110 rk3399 devicetree files in Linux. I count only 29
in U-Boot.

If we were to support Mediatek 8195, for example, we would ideally
like to support the Chromebooks and use a single Kconfig for all of
them. In general, if we make it easy, newer platforms will need to
follow the path of least resistance. The reason rk3399 is mostly
generic is that it was based on rk3288, which was written that way
from the start.

>
> > > The only win I see there is it would be part
> > > of what I've said before about how I do not want the "XPL" series you've
> > > talked about before, but instead think Yamada-san was right in hindsight
> > > and in short we should have "fooboard_defconfig",
> > > "fooboard_spl_defconfig" and "fooboard_tpl_defconfig" and you make each
> > > config and build each config by itself. In that context, yes, you could
> > > have barvend-fooboard_rev1_spl_defconfig,
> > > barvend-fooboard_rev2_spl_defconfig and barvend-fooboard_defconfig to
> > > get a more generic U-Boot build.  But nothing so much like an OS kernel
> > > because we care about binary size and rarely does the OS vendor (but
> > > some production cases in turn do), so outside of SoC-vendor where
> > > showing off features is more important than size, most of the time, will
> > > you see an actual use for SoC-generic U-Boot build.
> >
> > We'll see. The size cost for making things generic across an SoC is
> > likely very small, particularly if the settings are in the DT where
> > they belong. But I do accept we are not seeing the pressure yet.
>
> Yes, I think we're well past the point where it's a case of needing to
> see the implementation rather than talking about it over and over.

Yes, that is [1]. If you'd like to set a timeline I can take a look.
But we already have lots of examples, e.g. chromebook_bob/kevin, 4
chromebook/bits for rk3299. Quite a few of the sunxi boards are very
common, from what I can tell.

>
> > For XPL, there are pros and cons, but I thought we talked about that
> > at the time and agreed that the need for Kconfig dependencies between
> > phases makes having separate defconfigs too painful?
>
> I recall there being a large number of issues.

My memory is pretty dim about those, but I am sure there are issues to
resolve, as with anything new. I still believe it is the best way
forward. We should be able to add a new phase with a few build
changes, not the large effort needed today. Most of the prereqs were
applied, so perhaps it would not be a large series these days?

Regards,
Simon

>
> --
> Tom

[1] https://source.denx.de/u-boot/custodians/u-boot-dm/-/issues/15
[2] https://patchwork.ozlabs.org/project/uboot/list/?series=380278
Tom Rini Jan. 3, 2024, 1:03 a.m. UTC | #14
On Tue, Jan 02, 2024 at 04:51:34PM -0700, Simon Glass wrote:
> Hi Tom,
> 
> On Tue, Jan 2, 2024 at 7:55 AM Tom Rini <trini@konsulko.com> wrote:
> >
> > On Tue, Jan 02, 2024 at 07:06:36AM -0700, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Sun, Dec 31, 2023 at 7:01 AM Tom Rini <trini@konsulko.com> wrote:
> > > >
> > > > On Sun, Dec 31, 2023 at 05:45:00AM -0700, Simon Glass wrote:
> > > > > -Scott as it is bouncing
> > > > >
> > > > > Hi,
> > > > >
> > > > > On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
> > > > > >
> > > > > > On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> > > > > > >
> > > > > > > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > > > > > > Hi Tom,
> > > > > > > >
> > > > > > > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > >
> > > > > > > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > > > > > > Hi Tom,
> > > > > > > > > >
> > > > > > > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > > >
> > > > > > > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > > > > > > Hi Tom,
> > > > > > > > > > > >
> > > > > > > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > > > > > > .dtb files for that SoC.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > > > > > > subdirectories for each vendor.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > > > > > > same SoC.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > > > > > > >
> > > > > > > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > > > > > > >
> > > > > > > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > > > > > > to track that.
> > > > > > > > > > >
> > > > > > > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > > > > > > what's going on in this series.
> > > > > > > > > >
> > > > > > > > > > This seems to again be the disagreement over whether a single DT
> > > > > > > > > > should be build for each board, or all the DTs for an SoC?
> > > > > > > > >
> > > > > > > > > It's about the disagreement on what we should be building, and what that
> > > > > > > > > infrastructure looks like. I do not like adding extra rules for
> > > > > > > > > "clarity" because they don't make things clearer, they lead to the
> > > > > > > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > > > > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > > > > > > because we already have the rules and logic to ensure we build the
> > > > > > > > > required dtbs. I also don't like the parts of this series that amount
> > > > > > > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > > > > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > > > > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > > > > > > cases of "this could have been just a DT change", like
> > > > > > > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > > > > > > dir, but the configs are different and the dts are different, so I don't
> > > > > > > > > know that you could really just swap the dtbs.
> > > > > > > >
> > > > > > > > It is true that we have a different defconfig for each board, but IMO
> > > > > > > > that is not good. It is an artifact of the way the build system works.
> > > > > > > > IMO Kconfig should be used to define sensible defaults so that the
> > > > > > > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > > > > > > the mix, if we can agree on [1].
> > > > > > > >
> > > > > > > > But if we let this genie out of the bottle, it will be impossible to
> > > > > > > > put back in. The devicetree should control the hardware in U-Boot and
> > > > > > > > it should be possible to use the same U-Boot proper on all boards
> > > > > > > > which use the same SoC.
> > > > > > >
> > > > > > > We've never been past the point where a few examples of closely related
> > > > > > > boards can re-use the same U-Boot build and just change the device tree.
> > > > > > >
> > > > > > > It's going to be very SoC specific if we can ever do things like that,
> > > > > > > and it will also likely in turn become a question of where did the
> > > > > > > tricky bits that U-Boot used to do get shoved instead. You're not going
> > > > > > > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > > > > > > ignoring all of the other omap3 boards) and get one binary that works on
> > > > > > > both, and just uses DT. Let alone that no one wants to do that work.
> > > > > > >
> > > > > > > You've mentioned Rockchip before as maybe a better example, but
> > > > > > > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > > > > > > leading me to think that no, there's too much "this is what THIS
> > > > > > > hardware does" that means that no, there's going to be hardware
> > > > > > > variation that one must just handle in C. Or get more and new bindings
> > > > > > > accepted upstream to try and make that be data driven, and also possibly
> > > > > > > have to deal with "that's policy, not hardware" type arguments and so
> > > > > > > forth.
> > > > >
> > > > > Oh wow yes that is crazy! But you can always check the compatible
> > > > > string if really necessary. It would be nice to use a sysinfo driver
> > > > > for this sort of thing. I should just be a full-time code reviewer...
> > > > >
> > > > > >
> > > > > > Related I've seen issues with nearly identical rockchips devices that
> > > > > > use different memory chips that as a result need different U-Boot
> > > > > > builds because the early boot part needs to initialise a completely
> > > > > > different set of memory and the two different sets of rules aren't
> > > > > > detectable at run-time nor are they even small enough to fit into
> > > > > > smem.
> > > > >
> > > > > Some of the differences are real/important, like memory settings, some
> > > > > are not. For boards with enough SRAM that SPL can use DM/DT, we can
> > > > > deal with these.
> > > > >
> > > > > But even if SPL does need to be custom, that is better than having a
> > > > > full, separate U-Boot for every single board.
> > > >
> > > > I'm not sure that's a use case anyone else has or wants, and I disagree
> > > > that building a unique SPL and then more generic U-Boot is a win, in
> > > > practical and effort terms.
> > >
> > > Think about firmware update where you could have an update that
> > > supports all rk3399 boards, rather than 110 separate (and duplicate)
> > > firmware updates.
> >
> > I don't know who wants that actually is the problem I keep trying to
> > bring up. In other words, you're saying that the differences between
> > rock-pi-4c-rk3399_defconfig and khadas-edge-v-rk3399_defconfig are
> > unintentional and it's just due to different device trees and I say
> > they're intentional and the desire is not for a "kitchen sink" type
> > rk3399 primary U-Boot build. My evidence for this goes back to the SoCs
> > where we do have both "kitchen sink" and then board specific builds.
> > This would be things like how there's the am65x_evm configs, which
> > support all of the TI reference platforms (and others which follow the
> > EEPROM spec TI uses) and then also iot2050_defconfig, which also uses
> > the am65x SoC, but does not (would not) support the TI EEPROM layout and
> > instead does what it needs to do for their custom hardware revisions and
> > support all of those, instead.
> 
> OK, but this code should be in drivers which we can enable or disable,
> wouldn't it?

No, it's the board specific code. I mean I guess a few of the things
like "read EEPROM and see if it follows $my layout spec" could be
counted as a driver rather than board/$vendor/common/ code.  But the
rest of it isn't. Please look at the board examples I've listed above.

> We are trying to move away from board.c files.

We are? I didn't know that. We're trying to get rid of board.h, yes. And
some platforms where the rest of the firmware stack does everything else
needed, yes, we can avoid having dummy board.c files. That's the kind of
case where _maybe_ we could even have a generic-aarch64_defconfig (and
other platforms too? I _think_ the most recent example that maybe you're
thinking of was a MIPS-based router).

> I am not saying that all the defconfig differences are unintentional,
> just that we should really rationalise them, so it is clear what needs
> to be enabled for each board, and what is just by accident. Part of
> that is using Kconfig more than defconfig.

Yes, there might be some cases where the differences don't need to be
there, and maybe rk3399 is an example where more vendor boards could be
supported by a single config. But maybe not, there's a lot of annoying
board specific things that we need to care about that the OS then just
gets to inherit as having been handled.

> Another part might be
> fragments if we can agree a way to describe a defconfig made up of
> fragments ([2] is still hanging about).

Yes, I'm confused by what you're saying now here since the series here
is doing the opposite of what I thought you keep saying. This is making
"am62x_beagleplay_a53" be a specific thing to build for instead of just
making it be part of "am62x_evm_a53" as the only thing it changes is the
default device tree. And we're already always building the beagleplay
dtbs under the SoC name. That said, I'm not sure where functionally that
series ended up since beagleplay wants a different environment for LED
flashing and so forth.

> > What I think you keep wanting to aim for is fine and good and something
> > platforms can opt in to, and we have some doing it today. But it's still
> > at the end of the day a choice for the designers.
> 
> Indeed. I just want to make it easier to be generic than to be specific.

And in turn I don't know why we're hung up on "build more device trees"
when the first problem I see is "make some generic faux-boards and prove
them out".

> > You say "110 separate (and duplicate)" and I disagree with the "(and
> > duplicate)" part of that. Could some platforms be condensed? Yes,
> > likely. But figuring out how to do that starts with figuring out why
> > they're separate to start with.
> 
> I mean there are 110 rk3399 devicetree files in Linux. I count only 29
> in U-Boot.

I only see 41 dts files in v6.7-rc8 for "rk3399" and 27 defconfigs. So
yes, there's probably some level already of one U-Boot defconfig handles
N board revs. I agree there likely could be more.

> If we were to support Mediatek 8195, for example, we would ideally
> like to support the Chromebooks and use a single Kconfig for all of
> them. In general, if we make it easy, newer platforms will need to
> follow the path of least resistance. The reason rk3399 is mostly
> generic is that it was based on rk3288, which was written that way
> from the start.

Okay? A lot of the newer SoCs are done more generic than before,
especially on aarch64 compared with arm32 as some of the very board
specific stuff has been shoved to other parts of the stack already. I
keep bringing up TI K3 stuff because it too is done generically but also
we have in tree examples of intentionally NOT copying the reference
hardware platform and having true unique changes that need to be
handled.

> > > > The only win I see there is it would be part
> > > > of what I've said before about how I do not want the "XPL" series you've
> > > > talked about before, but instead think Yamada-san was right in hindsight
> > > > and in short we should have "fooboard_defconfig",
> > > > "fooboard_spl_defconfig" and "fooboard_tpl_defconfig" and you make each
> > > > config and build each config by itself. In that context, yes, you could
> > > > have barvend-fooboard_rev1_spl_defconfig,
> > > > barvend-fooboard_rev2_spl_defconfig and barvend-fooboard_defconfig to
> > > > get a more generic U-Boot build.  But nothing so much like an OS kernel
> > > > because we care about binary size and rarely does the OS vendor (but
> > > > some production cases in turn do), so outside of SoC-vendor where
> > > > showing off features is more important than size, most of the time, will
> > > > you see an actual use for SoC-generic U-Boot build.
> > >
> > > We'll see. The size cost for making things generic across an SoC is
> > > likely very small, particularly if the settings are in the DT where
> > > they belong. But I do accept we are not seeing the pressure yet.
> >
> > Yes, I think we're well past the point where it's a case of needing to
> > see the implementation rather than talking about it over and over.
> 
> Yes, that is [1]. If you'd like to set a timeline I can take a look.
> But we already have lots of examples, e.g. chromebook_bob/kevin, 4
> chromebook/bits for rk3299. Quite a few of the sunxi boards are very
> common, from what I can tell.

As soon as you're able, yes, please test and show multi platform builds
that extend beyond the multi platform builds we have today that
specify the N platforms they're able to function on.

> > > For XPL, there are pros and cons, but I thought we talked about that
> > > at the time and agreed that the need for Kconfig dependencies between
> > > phases makes having separate defconfigs too painful?
> >
> > I recall there being a large number of issues.
> 
> My memory is pretty dim about those, but I am sure there are issues to
> resolve, as with anything new. I still believe it is the best way
> forward. We should be able to add a new phase with a few build
> changes, not the large effort needed today. Most of the prereqs were
> applied, so perhaps it would not be a large series these days?

I believe the first few patches were adding some very large number of
"bool SPL_FOO" entries and that was a hard NAK from me as showing why
this makes life worse, not better.
Simon Glass Jan. 4, 2024, 1:40 a.m. UTC | #15
Hi Tom,

On Tue, Jan 2, 2024 at 6:03 PM Tom Rini <trini@konsulko.com> wrote:
>
> On Tue, Jan 02, 2024 at 04:51:34PM -0700, Simon Glass wrote:
> > Hi Tom,
> >
> > On Tue, Jan 2, 2024 at 7:55 AM Tom Rini <trini@konsulko.com> wrote:
> > >
> > > On Tue, Jan 02, 2024 at 07:06:36AM -0700, Simon Glass wrote:
> > > > Hi Tom,
> > > >
> > > > On Sun, Dec 31, 2023 at 7:01 AM Tom Rini <trini@konsulko.com> wrote:
> > > > >
> > > > > On Sun, Dec 31, 2023 at 05:45:00AM -0700, Simon Glass wrote:
> > > > > > -Scott as it is bouncing
> > > > > >
> > > > > > Hi,
> > > > > >
> > > > > > On Fri, Dec 29, 2023 at 9:46 AM Peter Robinson <pbrobinson@gmail.com> wrote:
> > > > > > >
> > > > > > > On Fri, Dec 29, 2023 at 12:23 AM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > >
> > > > > > > > On Thu, Dec 28, 2023 at 07:48:08PM +0000, Simon Glass wrote:
> > > > > > > > > Hi Tom,
> > > > > > > > >
> > > > > > > > > On Thu, Dec 28, 2023 at 3:40 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > >
> > > > > > > > > > On Thu, Dec 28, 2023 at 03:09:40PM +0000, Simon Glass wrote:
> > > > > > > > > > > Hi Tom,
> > > > > > > > > > >
> > > > > > > > > > > On Thu, Dec 28, 2023 at 2:23 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > On Thu, Dec 28, 2023 at 01:37:07PM +0000, Simon Glass wrote:
> > > > > > > > > > > > > Hi Tom,
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Wed, Dec 27, 2023 at 1:21 PM Tom Rini <trini@konsulko.com> wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Wed, Dec 27, 2023 at 08:23:56AM +0000, Simon Glass wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > U-Boot builds devicetree binaries from its source tree. As part of the
> > > > > > > > > > > > > > > Kconfig conversion, the Makefiles were updated to align with how this
> > > > > > > > > > > > > > > is done in Linux: a single target for each SoC is used to build all the
> > > > > > > > > > > > > > > .dtb files for that SoC.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Since then, the Makefiles have devolved in some cases, resulting in
> > > > > > > > > > > > > > > lots of target-specific build rules. Also Linux has moved to using
> > > > > > > > > > > > > > > subdirectories for each vendor.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Recent work aims to allow U-Boot to directly use devicetree files from
> > > > > > > > > > > > > > > Linux. This would be easier if the directory structure were the same.
> > > > > > > > > > > > > > > Another recent discussion involved dropping the build rules altogether.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > This series makes a start at cleaning up some of the build rules, to
> > > > > > > > > > > > > > > reduce the amount of code and make it easier to add new boards for the
> > > > > > > > > > > > > > > same SoC.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > One issue is that the ARCH_xxx Kconfig options between U-Boot and Linux
> > > > > > > > > > > > > > > are not always the same. Given the large number of SoCs and boards
> > > > > > > > > > > > > > > supported by U-Boot, it would be useful to align these where possible.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I don't know why we should start with this now, and further not being on
> > > > > > > > > > > > > > top of Sumit's series to remove our duplicate dts files. And that's
> > > > > > > > > > > > > > where we can have the conversation about for which cases it even makes
> > > > > > > > > > > > > > sense to build all of the dts files for a given SoC.
> > > > > > > > > > > > >
> > > > > > > > > > > > > This is a completely different series - there are no conflicts with
> > > > > > > > > > > > > Sumit's series so it can be applied before or after it.
> > > > > > > > > > > > >
> > > > > > > > > > > > > My goal here is to clean up our build rules, rather than just throwing
> > > > > > > > > > > > > them all away, for reasons we have discussed previously. I filed [1]
> > > > > > > > > > > > > to track that.
> > > > > > > > > > > >
> > > > > > > > > > > > Yes, I'm saying we shouldn't be doing anything this series does until
> > > > > > > > > > > > after Sumit's series has landed. Along with the fact that I don't like
> > > > > > > > > > > > what's going on in this series.
> > > > > > > > > > >
> > > > > > > > > > > This seems to again be the disagreement over whether a single DT
> > > > > > > > > > > should be build for each board, or all the DTs for an SoC?
> > > > > > > > > >
> > > > > > > > > > It's about the disagreement on what we should be building, and what that
> > > > > > > > > > infrastructure looks like. I do not like adding extra rules for
> > > > > > > > > > "clarity" because they don't make things clearer, they lead to the
> > > > > > > > > > unclear mess we have today getting worse. Most instructions are _not_
> > > > > > > > > > "now take this dtb and this binary and .." but just "take this binary",
> > > > > > > > > > because we already have the rules and logic to ensure we build the
> > > > > > > > > > required dtbs. I also don't like the parts of this series that amount
> > > > > > > > > > to deck shuffling when we should just be taking the chairs away. There's
> > > > > > > > > > just not nor will there be a case for omap3/4/5 platforms of "change the
> > > > > > > > > > dtb", so building more is pointless. For other SoCs, there may be some
> > > > > > > > > > cases of "this could have been just a DT change", like
> > > > > > > > > > rock5b-rk3588_defconfig / rock5a-rk3588s_defconfig could share a board
> > > > > > > > > > dir, but the configs are different and the dts are different, so I don't
> > > > > > > > > > know that you could really just swap the dtbs.
> > > > > > > > >
> > > > > > > > > It is true that we have a different defconfig for each board, but IMO
> > > > > > > > > that is not good. It is an artifact of the way the build system works.
> > > > > > > > > IMO Kconfig should be used to define sensible defaults so that the
> > > > > > > > > defconfigs are nearly empty. Perhaps config fragments can be part of
> > > > > > > > > the mix, if we can agree on [1].
> > > > > > > > >
> > > > > > > > > But if we let this genie out of the bottle, it will be impossible to
> > > > > > > > > put back in. The devicetree should control the hardware in U-Boot and
> > > > > > > > > it should be possible to use the same U-Boot proper on all boards
> > > > > > > > > which use the same SoC.
> > > > > > > >
> > > > > > > > We've never been past the point where a few examples of closely related
> > > > > > > > boards can re-use the same U-Boot build and just change the device tree.
> > > > > > > >
> > > > > > > > It's going to be very SoC specific if we can ever do things like that,
> > > > > > > > and it will also likely in turn become a question of where did the
> > > > > > > > tricky bits that U-Boot used to do get shoved instead. You're not going
> > > > > > > > to combine board/beagle/beagle/beagle.c and board/ti/omap3evm/evm.c (and
> > > > > > > > ignoring all of the other omap3 boards) and get one binary that works on
> > > > > > > > both, and just uses DT. Let alone that no one wants to do that work.
> > > > > > > >
> > > > > > > > You've mentioned Rockchip before as maybe a better example, but
> > > > > > > > https://patchwork.ozlabs.org/project/uboot/list/?series=383579&state=* was
> > > > > > > > leading me to think that no, there's too much "this is what THIS
> > > > > > > > hardware does" that means that no, there's going to be hardware
> > > > > > > > variation that one must just handle in C. Or get more and new bindings
> > > > > > > > accepted upstream to try and make that be data driven, and also possibly
> > > > > > > > have to deal with "that's policy, not hardware" type arguments and so
> > > > > > > > forth.
> > > > > >
> > > > > > Oh wow yes that is crazy! But you can always check the compatible
> > > > > > string if really necessary. It would be nice to use a sysinfo driver
> > > > > > for this sort of thing. I should just be a full-time code reviewer...
> > > > > >
> > > > > > >
> > > > > > > Related I've seen issues with nearly identical rockchips devices that
> > > > > > > use different memory chips that as a result need different U-Boot
> > > > > > > builds because the early boot part needs to initialise a completely
> > > > > > > different set of memory and the two different sets of rules aren't
> > > > > > > detectable at run-time nor are they even small enough to fit into
> > > > > > > smem.
> > > > > >
> > > > > > Some of the differences are real/important, like memory settings, some
> > > > > > are not. For boards with enough SRAM that SPL can use DM/DT, we can
> > > > > > deal with these.
> > > > > >
> > > > > > But even if SPL does need to be custom, that is better than having a
> > > > > > full, separate U-Boot for every single board.
> > > > >
> > > > > I'm not sure that's a use case anyone else has or wants, and I disagree
> > > > > that building a unique SPL and then more generic U-Boot is a win, in
> > > > > practical and effort terms.
> > > >
> > > > Think about firmware update where you could have an update that
> > > > supports all rk3399 boards, rather than 110 separate (and duplicate)
> > > > firmware updates.
> > >
> > > I don't know who wants that actually is the problem I keep trying to
> > > bring up. In other words, you're saying that the differences between
> > > rock-pi-4c-rk3399_defconfig and khadas-edge-v-rk3399_defconfig are
> > > unintentional and it's just due to different device trees and I say
> > > they're intentional and the desire is not for a "kitchen sink" type
> > > rk3399 primary U-Boot build. My evidence for this goes back to the SoCs
> > > where we do have both "kitchen sink" and then board specific builds.
> > > This would be things like how there's the am65x_evm configs, which
> > > support all of the TI reference platforms (and others which follow the
> > > EEPROM spec TI uses) and then also iot2050_defconfig, which also uses
> > > the am65x SoC, but does not (would not) support the TI EEPROM layout and
> > > instead does what it needs to do for their custom hardware revisions and
> > > support all of those, instead.
> >
> > OK, but this code should be in drivers which we can enable or disable,
> > wouldn't it?
>
> No, it's the board specific code. I mean I guess a few of the things
> like "read EEPROM and see if it follows $my layout spec" could be
> counted as a driver rather than board/$vendor/common/ code.  But the
> rest of it isn't. Please look at the board examples I've listed above.

Yes I agree those are unpleasant...but that is not the way it should
be done. We should have proper APIs and drivers for board-specific
things. If we can't do that, at least depend on a compatible string.
That sort of code would never be allowed in Linux, right?

>
> > We are trying to move away from board.c files.
>
> We are? I didn't know that. We're trying to get rid of board.h, yes. And
> some platforms where the rest of the firmware stack does everything else
> needed, yes, we can avoid having dummy board.c files. That's the kind of
> case where _maybe_ we could even have a generic-aarch64_defconfig (and
> other platforms too? I _think_ the most recent example that maybe you're
> thinking of was a MIPS-based router).

Maybe we could for U-Boot proper, yes. But think of all the drivers
you would have to enable...

>
> > I am not saying that all the defconfig differences are unintentional,
> > just that we should really rationalise them, so it is clear what needs
> > to be enabled for each board, and what is just by accident. Part of
> > that is using Kconfig more than defconfig.
>
> Yes, there might be some cases where the differences don't need to be
> there, and maybe rk3399 is an example where more vendor boards could be
> supported by a single config. But maybe not, there's a lot of annoying
> board specific things that we need to care about that the OS then just
> gets to inherit as having been handled.

Sure.

>
> > Another part might be
> > fragments if we can agree a way to describe a defconfig made up of
> > fragments ([2] is still hanging about).
>
> Yes, I'm confused by what you're saying now here since the series here
> is doing the opposite of what I thought you keep saying. This is making
> "am62x_beagleplay_a53" be a specific thing to build for instead of just
> making it be part of "am62x_evm_a53" as the only thing it changes is the
> default device tree. And we're already always building the beagleplay
> dtbs under the SoC name. That said, I'm not sure where functionally that
> series ended up since beagleplay wants a different environment for LED
> flashing and so forth.

I just think we are a bit lost here. To my reading that series creates
a fairly generic defconfig and then uses it on a few boards, with
minor variations. My point was that many of the differences are
unintentional or unnecessary. Yours is that many are intentional or
necessary. So I suspect we are in agreement, actually?

Any design decision involves tradeoffs and people have their own
weights on the things they care about, so will reach different
decisions or have different preferences. It is when one path is
completely closed off that things get difficult.

>
> > > What I think you keep wanting to aim for is fine and good and something
> > > platforms can opt in to, and we have some doing it today. But it's still
> > > at the end of the day a choice for the designers.
> >
> > Indeed. I just want to make it easier to be generic than to be specific.
>
> And in turn I don't know why we're hung up on "build more device trees"
> when the first problem I see is "make some generic faux-boards and prove
> them out".

OK

>
> > > You say "110 separate (and duplicate)" and I disagree with the "(and
> > > duplicate)" part of that. Could some platforms be condensed? Yes,
> > > likely. But figuring out how to do that starts with figuring out why
> > > they're separate to start with.
> >
> > I mean there are 110 rk3399 devicetree files in Linux. I count only 29
> > in U-Boot.
>
> I only see 41 dts files in v6.7-rc8 for "rk3399" and 27 defconfigs. So
> yes, there's probably some level already of one U-Boot defconfig handles
> N board revs. I agree there likely could be more.

Yes.

>
> > If we were to support Mediatek 8195, for example, we would ideally
> > like to support the Chromebooks and use a single Kconfig for all of
> > them. In general, if we make it easy, newer platforms will need to
> > follow the path of least resistance. The reason rk3399 is mostly
> > generic is that it was based on rk3288, which was written that way
> > from the start.
>
> Okay? A lot of the newer SoCs are done more generic than before,
> especially on aarch64 compared with arm32 as some of the very board
> specific stuff has been shoved to other parts of the stack already. I
> keep bringing up TI K3 stuff because it too is done generically but also
> we have in tree examples of intentionally NOT copying the reference
> hardware platform and having true unique changes that need to be
> handled.

OK. I see those as things to address, not fundamental flaws in the idea.

>
> > > > > The only win I see there is it would be part
> > > > > of what I've said before about how I do not want the "XPL" series you've
> > > > > talked about before, but instead think Yamada-san was right in hindsight
> > > > > and in short we should have "fooboard_defconfig",
> > > > > "fooboard_spl_defconfig" and "fooboard_tpl_defconfig" and you make each
> > > > > config and build each config by itself. In that context, yes, you could
> > > > > have barvend-fooboard_rev1_spl_defconfig,
> > > > > barvend-fooboard_rev2_spl_defconfig and barvend-fooboard_defconfig to
> > > > > get a more generic U-Boot build.  But nothing so much like an OS kernel
> > > > > because we care about binary size and rarely does the OS vendor (but
> > > > > some production cases in turn do), so outside of SoC-vendor where
> > > > > showing off features is more important than size, most of the time, will
> > > > > you see an actual use for SoC-generic U-Boot build.
> > > >
> > > > We'll see. The size cost for making things generic across an SoC is
> > > > likely very small, particularly if the settings are in the DT where
> > > > they belong. But I do accept we are not seeing the pressure yet.
> > >
> > > Yes, I think we're well past the point where it's a case of needing to
> > > see the implementation rather than talking about it over and over.
> >
> > Yes, that is [1]. If you'd like to set a timeline I can take a look.
> > But we already have lots of examples, e.g. chromebook_bob/kevin, 4
> > chromebook/bits for rk3299. Quite a few of the sunxi boards are very
> > common, from what I can tell.
>
> As soon as you're able, yes, please test and show multi platform builds
> that extend beyond the multi platform builds we have today that
> specify the N platforms they're able to function on.

OK

>
> > > > For XPL, there are pros and cons, but I thought we talked about that
> > > > at the time and agreed that the need for Kconfig dependencies between
> > > > phases makes having separate defconfigs too painful?
> > >
> > > I recall there being a large number of issues.
> >
> > My memory is pretty dim about those, but I am sure there are issues to
> > resolve, as with anything new. I still believe it is the best way
> > forward. We should be able to add a new phase with a few build
> > changes, not the large effort needed today. Most of the prereqs were
> > applied, so perhaps it would not be a large series these days?
>
> I believe the first few patches were adding some very large number of
> "bool SPL_FOO" entries and that was a hard NAK from me as showing why
> this makes life worse, not better.

I believe that was an earlier version. The later versions used a
'nospl' file to mark things that were 'global' across all builds. But
another look and a rebase would be needed to check that.

Regards,
Simon